Process of making magnesium sulfate.



, No. 7l4,984. j Patented U00. 2, 1902.

H. H. WING.

PROCESS OF MAKING MAGNESIUM SULFATE.

. (Application filed. S apt. 5, 1901.) (Nu m...)

UUUH Uirno STATES PATENT OFFICE.

HERBERT II. WING, OF NEW BRIGHTON, N'EVV YORK.

PROCESS OF MAKING MAGNESIUM SULFATE.

SPECIFICATION forming part of Letters Patent No. 714,984, dated December 2, 1902.

Application filed September 5, 1901. Serial No. 74,375. (No specimens.)

To all whom it may concern:

Be it known that I, HERBERT H. WING, a citizen of the United States, residing at New Brighton, in the county of Richmond and State of New York, have invented certain new and useful Improvements in Processes of Obtaining Magnesium Sulfate and By-Prodnets; and I do hereby declare the following to bea full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

The object of my invention is to utilize sulfur fumes in the production of chemicals in the place of other and more expensive chemicals which have hitherto always been used in the commercial production of such chemicals and also to use sulfur fumes which are too dilute for any other known purpose. The dilute sulfurous fumes (less than one per cent. S0,) which I have used could not be applied for the manufacture of liquid sulfurous acid by absorbing these fumes in water and then expelling the pure gas by heat, as such dilute gases will not produce strong enough sulfurous-acid solutions to be thus used commercially.

In the drawings hereto attached, Figure 1 is an elevation, partly in section, of apparatus suitable for the carrying out of my invention; and Fig. 2 is a sectional elevation of a furnace which may be used in conjunction therewith.

By my process I am also able to use sulfur fumes which are contaminated with air or with air and carbonic-acid gas or with sulfuric-acid gas. Besides being able to use sulfur fumes, which are a waste product and often a great nuisance and in many cases have to be got rid of at great expense, the chemicals which I produce from such fumes are at present produced by expensive chemicals, such as sulfuric acid or sodium sulfate and calcium chlorid, carbonate of magnesia, and sulfuric acid, (be.

My process, in general terms, consists in first producing a mixture of the sulfite and sulfate of magnesium by bringing the sulfur fumes and air into contact in the presence of moisture with magnesia, magnesium hydrate, magnesium carbonate, or any compound of magnesium which is decomposable by sulfur dioxid in the presence of moisture. The proportion of sulfite and sulfate will depend on the amount of oxidizing that the sulfite undergoes from the amount of air brought into contact with it and also on the amount of sulfuric acid contained in the fumes and produced in the passage of the gases through the apparatus. The temperature also influences the result, the higher temperature increasing the amount of sulfates produced. By continuing to pass the fumes through the solution of the sulfates and at the same time adding fresh quantities of magnesia compounds the oxidizing of the sulfite formed (which being insoluble remains suspended in the solution)'is increased, and these conditions for obtaining the sulfate can be regulated so that all or substantially all of the sulfite is converted into sulfate. In this case the solution is allowed to stand and the insoluble impurities settled out and the pure sulfate of magnesia obtained by crystallization. Instead of completing the oxidation of all the sulfite directly in the liquor the sulfite can be settled or filtered out and slightly heated in a drier or reverberatory furnace and exposed to an oxidizing atmosphere, when it will be very rapidly converted into sulfate.

The sulfate thus produced is then added to water and dissolved, the insoluble impuri ties settled out, and the pure sulfate crystallized and recovered.

Instead of having the sulfate of magnesium the sole product of the utilization of the sulfur fumes, which necessitates the purchase of all the magnesium in some form decomposable by sulfur dioxid in the presence of moisture-such as oxid, hydrate, or carbonatcthe cost of this item can be reduced by carrying out the following reactions: The whole or part of the sulfate .of magnesium is brought into contact with a solution of calcium chlorid whereby there is produced calcium sulfate and IOO cially known as crown-filler or pearl-hardening. To the solution of magnesium chlorid I add lime or milk of lime, whereby there is produced magnesium hydrate and calcium chlorid. The magnesium hydrate being insoluble, it is precipitated, and the liquor containing the calcium chlorid is then decanted. The magnesium hydrate thus produced can be used over again in the first step of the process, and the regenerated calcium chlorid can also be used over again in the third step of this process.

Instead of using lime containing only the oxid of calcium, as above mentioned, I can use lime obtained from dolomite, and therefore containing both calcium and magnesium oxids. When this kind of lime is used, more will be required, as only the calcium hydrate in the same acts on the magnesium chlorid;

but the magnesium oxid in it will be converted into magnesium hydrate and will be obtained as such, along with the magnesium hydrate, from the magnesium chlorid, so that as much magnesium hydrate is obtained as a by-product as is contained in the dolomite lime. Wherever lime or dolomite lime is to be used, it may be used either in the form of lime or as milk of lime, as may be preferred, the milk of lime being in all respects equivalent to the lime in the reaction herein described. As the magnesium hydrate which is thus obtained is more valuable than calcined magnesia or magnesite at certain localities, the latter forms of magnesia may be used instead of the former for the first step of this process, in which case the final products will be all the magnesium hydrate from the calcined magnesia or magnesite and that of the dolomite lime and also the crown-filler or pearl-hardening, while the only materials which require to be purchased are calcined magnesia or magnesite and ordinary dolomite lime.

In case only a part of the magnesium sulfate was used to carry out the above-mentioned reaction the final products will be magnesium sulfate, all the magnesia of the magnesium sulfate used in the above reactions, and the corresponding amount of crown-filler or pearl-hardening, while the only materials which require to be purchased are calcined magnesia or magnesite and ordinary dolomite lime, and in case the magnesium hydrate produced was used for the first step of the process there would be less of it obtained as a final product, and thereby the necessity of buying any calcined magnesia or magnesite would be obviated, as the dolomite lime would be the only product to be bought and would furnish the necessary magnesia to produce the magnesium sulfate, which was not used in the subsequent reactions, beginning with the calcium chlorid, but which constituted one of the final products.

To carry out my process of utilizing sulfur fumes, a variety of different forms of apparatus may be used.

In the annexed drawings, which are elevations partly in section, I have shown in Fig. 1 a form of apparatus which is adapted for such work.

X represents a source from which fumes containing sulfur dioxid may be obtained and maybe a' smelting-furnace, ore-roaster, or any apparatus from which fumes containing sulfur dioxid can be obtained.

A represents a dust-collecting chamber for settling out any dust carried by the fumes.

T T represent pipes which convey the fumes to the absorbing apparatus L, which consists of a tank provided with means E for agitating the contents and mechanism G for operating the agitators E E.

H represents a receiving-tank, preferably mounted on trunnions and in which is provided a perforated false bottom it and filter: ing material 72 This tank is connected by suitable flexible connections h to a pump I, whereby the liquid contents of tank H may be drained away from the solid matter, leaving the latter semidry.

M represents a trough or conveyer into which the drained contents of tank H may be emptied, as by tipping the same on its trunnions, and by which conveyor the contents of tank H may be conducted to any other desired apparatus-as, for instance, to a drier.

0 represents a tank for crystallizing the magnesium sulfate, and P a tank for preparing the milk of magnesia or any compound of magnesium which in the presence of moisture is decomposable by sulfur dioxid.

R represents a pump for forcing the magnesiu m emulsion from tank P into the absorbing apparatus L.

S is a pipe connecting the pump R with the absorbing apparatus L.

D and O are tanks for treating the magnesium sulfate and the magnesium chlorid.

F is a pump, and K and J are inlet and outlet pipes to said pump, by means of which the liquid contents of tanks 0 and D may be transferred from one to the other or to the tank P. I

The method of operating the apparatus shown in the drawings consists in first passing the sulfur fumes containing SO with some air and more or less SO frOm the source X through the dust-settling chamber A, then through pipes T T and the absorbing apparatus L, through which they are drawn by by pipe to by means ofthe suction maintained by the suction-blower U. The absorbing apparatus L is nearly filled with an emulsion of magnesium hydrate or of any compound of magnesium which in the presence of moisture is decomposable by sulfur dioxid, which is prepared in the tank P and delivered to dized, to sulfate as beforefstated. Instead oftank L is then op e ned and thetcontents of'thei-absorber are, discharged into the filter i l rconverted finto sulfate Fa 1 3o wIIlQflIjlSi sue] foninstance'zastheconve er M and in, which, nmates the material is, V eated and subjected to the action; ofair admitted in any suitable manner, as through the door,

' crystallize with the first portion of,mag v nes um sulfate. Theinsoluble im uritiesfm J i z e d and thereby converted into monosulfite of: the tank ,H by the pump I, leaving, a 25 V offmagnesium: is removed vfrom the tank H} iifneedbe through theopening n, through a L the sulfate, producing a concentrated- $011 50 l we from crystallizing the Vina fate can be used to makeup t e emulsions; in the tank P until they are used so :often' a The crystallized ma ob tamedby the above met 'od is'then'aldded to ence of moisture isdecomposable by sulfur a solut n v V a ntalned dioxid, thefmonosulfite and; sulfate of magin the; tank Dy wherebycalcium sulfate nesiumare produced, the proportion of sul- CaSO,',2 H O,) andajsolutlon ofvmagne fateincreasing according to .the-amount'of s umchlo'r d (MgQl ),arei producedgoas .be;- $0. theamount of. air in the :fumes, the

fore I described. The insoluble; .Gfllcium: sul lengthoftime the fumes are drawnthrough fate is separated.if i;om the solutionyiwashed theliquonyand the temperature of thesame; and preferably dr1ed, 1n wh 1ch condit on it until. in time allthe monosulfite can be oxi: JS'kllOW n in,the,market ascrowmfillerflor pearl 5 hardening. v The solution; of magnej e sium :chlorid which is -produced -as; above. 75 st d. s; a orc y? p mp a imam tank (1. Into thisso ution limeyorlas an equivalent gmilk of; lime,; 1s; L added, whereby calciumflchlorid, is ,regenerated;,(:which; can 21; 1 8 over again), d; a ium drateis eproduced, which'bein I insolub precipitated. The calcium,- ch orid: sol is pumpjed-l backv into? the tank D; yflo n ent ma ne m ydr elpr I then pumped to the tank P, from, all" H isforced into. the absorber Lito ,beiused owe e m-Or it m yb W she d t na ei ni t i d,

of oxidizing all the monosulfiteflfirst produced in the liquor, the passage of thefumes is -preferably continuedgonlyguntil all the magnesia contained in the liquor is neutral= and sulfate, which can be ascertained by testing the liquor for acid or-alkaline reaction. The valve Z in i the discharge pipe tank H. LThe monosulfite of magnesium: is a whitish granular mud, from which a, part. of the water, is drained v,by.drawing it through the filter and perforated bottom I semi-dry'mass ,in the tank. The monosulfite jof $111116;

and is exposed to aheat=ina drier or furnaoe,

in an oxidizingatmosphere; whereby the this purpose afurnace. suchgas shownin Fig, 2' maybe emp1oyed,in,which N represen'ts ,a reyerberatoryfurnaceto which the benconveyed by any suitable or opening w and the ;charge may be stirred Wheneme th tier; (1' containing sulfurwdioxld and air desire to exclude the @presence; of l the sulfur i trioxid, which; will V8 1 y accjord-h ing to the source from'which. the;- umes-are; obtained; and which. as T before mentioned can be a, constituent of th i fumes which- 1 which then convertedxto sulfate the charge may alsobe withdrawn. [Thesolution passing through the filter in His forced by thej pump I through-the pipe 11 into the tank 0, where it is allqwcd to remain and. the mag nesium sulfate in solution is, crystallized, out. QThe sulfate producedin the drier or furnace is placed in .theItank H,and sufli?, cient hot water is added toiitj toi dissolue lid tion, then the pump .1 isQstartedflandithe clear solution of magnesium sulfate, is it pumped into. the; tainkQO. and;allowed to tlngi H 7., sable ul theplben istiireto he action of ulfur-qfumesi {In I 17 ;I,ll, .iil1:5t'h6v= presence of moisture, where ,lfitm I ndeel ate qhm gnes xa; erewprodu'ced, an as toicontaintoo great an amount ofim-qthengexposing such; mixture of sulfitemndri pur1ties, when fresh water is. usedin place sulfatetopxidizinglconditionsy wherebytheu of" the impure mother liquors which are .sulfite is; converted intosulfatew m thrown awa V Y Z 2, T e hereindescribed process of obtain in magnesium sulfate ,wiq'hichwconsists su jecting any compound of the monosulfite 'areleftfon the teri in 1 and are then removed. The mother liquors siumgsul-a ofmagnesi'u'm are produced, then'ex'p'osing jectin anyc'ompound of magnesium -decom'-' posabl e by sulfu'rdiokid in the presence of moisture, to the act'io'nof sulfur fumes containing sulfuf dioxid and air in the presence 7 f; m i t r h reby zthe sulfite "and "sulfate 7 ver'ted'finto "sulfate theni ci ystalliz'ingbuti sameinwatei'.

the ma nesium sulfate afso'l'utioii of the -4'. The"hereii1;,descilbed processfof obtain 1ng; 1'11agnesiumsulfate whicli=cons1sts'ln'sub V je'ct n'g "magnesiumfhydrate to the ac-tlon of sulfur fumes containingsulfur dioxid and the, mixture is converted into] sulfatei thenc 'yst'zill-izinfg" f out the ma nesium J sulfate from a solution-ofthfes'amei'in'Water;" -J"f j "5'." ;The liel ein' described piocessiof obtain! 'ingqma'gnesi um sulfatfewliich'consists-in sub magnesium 'sulfate then ex osing the sulfite to oxidizing conditions Wherebyfthe.

' is convertedintosulfate.v

, taining sulfur dioxid' andfai'iifi the pi'esence "of moisture; whereby the sulfiteand'sulfate moistureto' the} action of sulfur" fumes con of magnesium are'pioduced; theii 'sep aiatii'ig the soluble sulfateiin 'wat'erfrom theinsolu vma'gnes'iumsulfate, then'exposingt iie ofthe same iIi WaterJ V '7'. The herein desci'ibed'pi'ocess o obtain-""3 in'g magnesium sulfate and; a.by 'product which consists in subjecting any compound of magnesium decomposable by- 'sulfuijkdi oxidin' the presence of moisture; to the ac- .;tion of sulfur I fumes *containingl' sulfu dijectmg any-compoundof ma nesium deco po'sable by sulfur dioxid' in'the presence of: moisture to the action of'sulfur fumes con-i taining sulfur dioxid'and air 'inthe presence" of mo1sture',whereby the 'sulfi'te and sulfatei of'magnesium are-- r'odliced ,"thenfsepti'ating we the soluble sulfate in" Watei from the insolu blesulfite; subsequently ciry'sta'llizing;out'the;

1 6. The 1 herein described process of obtains ingma-gnesium sulfateyvhic'h consists'in sub jecting any, compoundof magnesium d m= posable bysul'fur dioxid' in the: 'p esenc'e" V I v U 22'': r 5d: if: 10; The herein described pi'ocefssjofobta m ing magnesium sulfate" by; 'p'ioducts'...

oxid and air in the'presence of moisture,

-whereby the sulfite' andsulfateof'mag nesium ai'e produced, then separating the soluble sulfate in water 'fromthe insoluble sulfite, then exposing the s'ul-fite to "oxidiz ing conditions, Whereby'the sulfiteiscon verted into sulfate, then "adding "thf sul fatetof a solution of calcium chlorid Where 7 by magnesium lchlorid and calciumj'sulfafi are produced, lthen separating the v insoluble calcium sulfate from the liquor lnwvhich 1t Was'produced,then adding lime to the mag magnesium hydrate al -'6 proivhich consists; in subjecting any compound of i n'lagnesii' m' decomposable by sul'fu'r dL oxid' in the presence; of moisture, to the ac tion: ofsulfur fumes containingsiilfun di-l oxidf a nd air in the pi'esence 'oiti inoistu 'e,v

whereby] the sulfite *andf sulfate f of -ma'gnesimn are produced, then- V separating the.

soluble sulfate in'watenfroin the insoluble ing conditions, whereby: the sulfite is convented 'iiito' sulfate; then adding thefsul'fate tof a solution of"calclium chlorid whereby magnesium 'chlorid and calcium siiilfate aifef 7 produced, themsepa atingf the insoluble cal ciumsulfate from the liquor in vwhich it was j produced, thenfadding chlorid and th'e by pljodiic t finag 1 y F drate are produced;

which consists in subjecting any [compound of magnesium decomposable bysulfuif dioxid;

* We r t the magnesium chlorld ri h jremains t-g solution in said; l quor,,lwhrehy c um.

i9: The hereinfdesc'i jihefd" proce s at 513mm? 7 mg" magnesium sulfate and by products Ice in the presence ofzmoistu're, to the action of sulfu fumes containing sulfur: dioxid and a r 1n. the pfesence of 'mOlst-tll'," whereby the sulfite and sulfate "of magnesium ere: 'pi'odujc a e eXPQ ng' sil himixtur vof i ullfi e; and: sulfate {to oxidizing; conditions whereby. t the 'sulfite converted into 4 sulfate};v then j addingafpo'rtion of-saidsu'lfate to av solutiol'l} film h r d. [w re y Y ma nesium l rid and. the by product cal'cium' sulfate; 7

p p 1 are produced,"ithen'sepaiatingthe insolubleQ ble' s'ulfite',= subsequently cfjtalli'zih out the i i x su'l' fite' "to oxidizing condit'ions Whefby' the: sulfite f" isv converted 5 into sulfate, then crystallizii'ng" out the magnesium sulfate from the solution" calcium sulfate from the: liquoi gin which it ounde th n' ddi grc l iiumhyd te to the magnesium chlorid jghich remained 5 Wllfil'eby j k f ium solution "in said 'li uo chloridii andsfma nesium ll ydirate' are pwhich onsists subjecting any compou lidlfr of inagnesiumdeco'mposablebysulfur dioxid' in the presence of moisture to the actiohjof' 'sulfui containing sulfur" idiox id Lari/d air in the presence of moisture, whereby the sulfite and sulfate of magnesium are produced, then continuing the action of said fumes until the sulfite of the mixture is converted into sulfate, then adding a portion of said sulfate to a solution of calcium chlorid whereby magnesium chlorid and the by product calcium sulfate are produced, then separating the insoluble calcium sulfate from the liquor in which it was produced, then adding calcium hydrate to the magnesium chlorid which remains in solution in said liquor whereby magnesium hydrate and calcium chlorid are produced.

11. The herein described process of obtaining magnesium sulfate and by products which consists in subjecting any compound of magnesium decomposable by sulfur dioxid in the presence of moisture, to-the action of sulfur fumes containing sulfur dioxid and air in the presence of moisture, whereby the sulfite and sulfate of magnesium are produced, then continuing'the action of said fumes until the sulfite of the mixture is converted into sulfate, then adding a portion of said sulfate to a solution of calcium chlorid whereby magnesium chlorid and the by product calcium sulfate are produced, then separating the insoluble calcium sulfate from the liquor in which it was produced, then adding calcium hydrate to the magnesium chlorid which remains in solution in water from the insoluble sulfite, then exposing the sulfite to oxidizing conditions whereby the sulfite is converted into sulfate, then adding a' portion of said sulfate to a solution of calcium chlorid whereby magnesium chlorid and the by product calcium sulfate are produced, then separating the insoluble calcium sulfate from the liquor in which it was produced, then adding lime or milk of lime to the magnesium chlorid which remains in solution in said liquor, whereby" magnesium hydrate and calcium chlorid are produced.

In testimony whereof I hereto aflix my signature, in presence of two witnesses.

HERBERT H. WING. Witnesses T. H. SPRATT, F. I. RIEFF. 

